Скачать или смотреть How to Get isSelected Value from a Child View in Parent View using SwiftUI

Learn how to manage state in SwiftUI by passing child view variables up to the parent view effectively.
---
This video is based on the question https://stackoverflow.com/q/70527963/ asked by the user 'New iOS Dev' ( https://stackoverflow.com/u/4622363/ ) and on the answer https://stackoverflow.com/a/70536260/ provided by the user 'jnpdx' ( https://stackoverflow.com/u/560942/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: How to get variable value of child view in parent view on SwiftUI?

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Managing State in SwiftUI: Accessing a Child View's Variable in a Parent View

SwiftUI has revolutionized the way we build user interfaces for iOS applications. One of the primary concepts in SwiftUI is state management, where data is passed around between parent and child views. Often, a common challenge developers face is how to retrieve or react to changing values in child views from their parent views. This post will address that problem by explaining how to effectively pass and manage state in SwiftUI, specifically when working with a child view called CancelRow and its isSelected binding.

The Problem: Accessing isSelected from CancelRow in a Parent View

In our scenario, we have a child view CancelRow with a binding variable isSelected. This variable represents whether the checkbox within the CancelRow is selected or not, and it can change based on user interaction. Our goal is to reflect these changes in the parent view, where we also want to control a SubmitButtonView. Here's the layout of the issue:

CancelRow: A view that includes a checkbox that toggles the isSelected state.

SubmitButtonView: A view should become active or inactive based on the isSelected state of CancelRow.

To achieve this, we need to ensure that the parent view owns and manages the state of isSelected. Let's walk through the solution step-by-step.

The Solution: Passing State from Parent to Child

Step 1: Define the State in the Parent View

The first step is to define our state variable in the parent view. We will use the -State property wrapper to create a boolean variable that will keep track of the isSelected state. Here's how to do that:

[[See Video to Reveal this Text or Code Snippet]]

Step 2: Modify the CancelRow to Accept the Binding

Next, we ensure that CancelRow accepts a binding variable. Instead of a custom initializer, we can use SwiftUI's synthesized initializer, which simplifies the code. Here’s how the modified CancelRow looks:

[[See Video to Reveal this Text or Code Snippet]]

Step 3: Access the State in the SubmitButtonView

The SubmitButtonView can now respond to the isSelected state from the parent view. You can directly use the boolean variable to decide if the button should be active or not:

[[See Video to Reveal this Text or Code Snippet]]

Final Code Example

Here's how everything looks together in the ContentView:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

By managing the state in the parent view and passing it down to the child views using -Binding, we achieved a clear, elegant way of keeping track of user interactions. This approach allows your SwiftUI app to remain reactive and maintain a single source of truth regarding the state.

Hopefully, this guide has clarified how to easily access and manage child view variables in a parent view within SwiftUI. Happy coding!